Firearms are equipped with triggers whereby the firearm may be discharged by the shooter. Trigger mechanisms are designed according to the firearm type and the purpose for which the firearm is intended. The trigger mechanism and its associated safing mechanism must not be prone to accidentally permitting or causing the firearm to discharge until the shooter deliberately pulls the trigger. Each type of firearm has unique trigger and safing requirements. This specification generally pertains to rifles; and particularly to bolt action high-power rifles, which shall be referred to as “rifle(s)” hereinafter, but application of the present specification to other firearms is not precluded.
There exists at least one prior art commercially available two-stage trigger that does not function as a typical military two-stage trigger. However, prior art “two-stage trigger” hereinafter refers to the typical military two-stage triggers such as employed in the M1903 Springfield and the M98 Mauser type rifles.
The word “safety” is used in several connotations in this specification. Hereinafter, “mechanical safety” refers to the structural and/or physical characteristics of the mechanical components being discussed. “Safety selector” refers to the safety lever or switch the shooter manipulates in order to set the rifle between “safe” and “fire.” Other connotations such as, “ . . . safety of bystanders . . . ” can be determined from the context.
The ideal rifle trigger mechanism possesses the following characteristics: 1) prevents the rifle from being accidentally discharged, as a result of rough handling, such as from dropping the rifle; irrespective of the safety selector setting; 2) prevents the rifle from accidentally firing as a result of slamming the bolt closed when vigorously manipulating the bolt; 3) consistently provides a crisp, clean “let-off” at exactly the same trigger-pull weight and displacement; 4) is adjustable for both trigger-pull weight and for the elimination of trigger “creep”; and 5) automatically and immediately resets back to its fully seared position after a partial pull and release of the trigger.
The ideal safety (including the mechanism that prevents firing, as well as the safety selector that interfaces with the shooter) possesses the following characteristics (when the safety selector is set to the “safe” position): 1) infallibly prevents the rifle from firing if the trigger is accidentally pulled (or bumped); 2) infallibly prevents the rifle from firing as a result of rough handling, such as dropping the rifle; 3) immediately informs the shooter at a glance and/or by “feel” (including blocking trigger movement) that the safety selector is on “safe”; 4) possesses ergonomic characteristics that permit the shooter to conveniently move the safety selector from “safe” to “fire” with minimal disturbance to aim and with minimal motion of the shooter; 5) is silent as the selector is moved from “safe” to “fire”; and 6) detents into its safe and fire positions without allowing any intermediate positions.
Rifle triggers fall into three general categories: 1) single-stage triggers; 2) two-stage triggers; and 3) set triggers. Set triggers are a specialized form of trigger, which are not discussed in this specification. Safeties for rifle triggers fall into two broad categories: 1) safeties that block the firing pin/striker; and 2) safeties that block the trigger or some intermediate part(s) between the trigger and the firing-pin/striker/hammer.
Since the late 19th century two-stage triggers have been employed in most military bolt action rifles. Military two-stage triggers are reliable, safe, easily mass produced, and foster sufficient accuracy so that a reasonably well trained soldier can hit an enemy soldier at moderate combat ranges. However, mass produced military two-stage triggers are not conducive to precision accuracy. In firing a rifle equipped with a two-stage trigger, the first stage of the trigger-pull consists of taking up a substantial amount of slack against friction and spring resistance. At the end of the slack portion of the trigger-pull, the second stage is contacted. The second stage provides significantly more resistance to the trigger, so that by increasing pressure on the trigger, the rifle is fired with real, but ideally indiscernible, further movement of the trigger.
Military two-stage triggers excellently meet the first and primary requirement for a rifle trigger, which is to prevent the rifle from being accidentally discharged as a result of rough handling, such as from dropping the rifle. Prior art two-stage triggers also fully meet the second major requirement which is to prevent the rifle from accidentally firing as a result of slamming the bolt closed when vigorously manipulating the bolt.
A major problem with conventional military two-stage triggers relative to precision marksmanship, however, is that conventional two-stage triggers are susceptible to “creep” at let-off. Trigger creep is the discernible movement of the trigger during the second stage of trigger-pull while moving toward let-off. While second-stage trigger creep before let-off has long been accepted as a fact of life in military rifles, trigger creep is anathema to precision riflemen. This creep could be gunsmithed out of the triggers, but this would not be practical on a mass produced scale, and the modified components would no longer be interchangeable, which would be unacceptable to the military. Another problem relating to mass produced prior art two-stage military rifle triggers relates to trigger-pull weight. The lower trigger-pull weight limit is governed by the force of the striker spring pressing the cocking-piece against the sear. The trigger spring must be strong enough to infallibly reset the trigger and sear to the relaxed position against the force/friction of the cocking-piece if the trigger is partially pulled but then released if the shooter decides not to fire. In other words, the trigger-pull weight can never be less than the trigger return spring force.
Prior art two-stage trigger design and function problems are further exacerbated by the necessarily relatively loose fit of the rifle bolt with the receiver. Military rifle receivers and bolts are designed with a substantial amount of clearance between each other in order to accommodate sand and dirt that inevitably contaminates rifles in typical combat environments. In addition to this designed clearance, the parts are also manufactured to dimensional tolerances which can further increase the clearance. This means that the position of the rear of the bolt can vertically occupy a range of positions from shot to shot.
This is important, as the position of the bolt/cocking-piece within the receiver directly affects the amount of engagement that the sear and cocking-piece will have. This is because, unlike most single-stage triggers which are “modular” or self-contained units (i.e. the components responsible for sear engagement are affixed into the same assembly), most two-stage trigger firing mechanisms are separated into two parts. The first part consisting of the trigger and sear is attached to the bottom of the receiver, while the second part consisting of the cocking-piece is a part of the bolt. Because the bolt with the cocking-piece is free to “float” inside the receiver, the amount of cocking-piece engagement with the sear, which is attached to the receiver, is variable.
Because it is unacceptable to allow a rifle which has a two-stage trigger to fire before the second-stage of the trigger pull is reached, the total sear/cocking-piece engagement must be sufficient (excessive) to cover all possible bolt/cocking-piece positions. Consequently, trigger creep will always occur when the rear of the bolt is positioned low in the receiver because under this condition the sear must be pulled down a significant distance in order to drop below the cocking-piece to fire the rifle. Military rifles used for sniping or for target shooting often have their two-stage triggers “gunsmithed” (altered) to eliminate creep. This practice is common and very effective in meeting the requirement for a crisp, clean let-off at the same trigger-pull weight from shot to shot. However, unless the work is performed by a skilled gunsmith, rifles so altered are more prone to malfunction (e.g. fire during the first stage, or suffer “doubles” in semiautomatic rifles) than unaltered triggers. Furthermore, gunsmithed trigger components are no longer safely interchangeable. Many rifle triggers have been rendered unsafe or ruined by poor gunsmithing.
Historically the solution to trigger creep in mass produced commercial bolt action rifles has been to employ modular single-stage triggers which interpose a sear prop or secondary sear between the trigger and the cocking-piece in the bolt. While single-stage triggers provide the solution to the trigger creep problem of military type two-stage triggers, single-stage triggers introduce their own problems. In single-stage triggers the contact between the trigger and the sear provides only an extremely fine engagement (0.005 to 0.015 thousandths of an inch). When the safety is “off,” this small engagement is all that prevents accidental discharge when the rifle is loaded and cocked. This potentially dangerous condition inherently exists when slamming the bolt closed, or jolting or dropping the rifle, which can jar the rifle/trigger sufficiently to fire the rifle. This flaw has resulted in a number of deaths of bystanders, as well as much litigation against well-known rifle manufacturers who produce otherwise excellent rifles.
Another shortcoming of single-stage triggers is that the shooter “feels” the entire weight of the trigger-pull at let-off. However, with a two-stage trigger, the shooter only “feels” the additional (cumulative) weight of the second stage. That is, while technically (with everything else being equal) a single-stage trigger will sear-off at the same “poundage” as a similarly set two-stage trigger, the two-stage trigger will only “feel like” the weight of the second stage as the shooter has already felt and compensated for the weight of the first stage. While this is mostly a matter of perception (psychological), the actual force needed to overcome the second stage is less when the pressure exerted on the first stage is viewed as a “preload.”
The safety selector of most single-stage triggers function by blocking the sear from moving. Other safety selectors block the movement of the trigger or cocking-piece, etc. In the types of trigger assemblies where the sear is blocked, it is absolutely critical that the sear be lifted slightly from the trigger during safing. That is, the safety must cam the sear away slightly from the trigger in order to ensure that the sear cannot drop off of the trigger in the event that the trigger is accidentally pulled or bumped while the safety selector is on “safe.” Failing to achieve the needed trigger/sear separation would allow the sear to drop off of and get below/behind the trigger. In this event the trigger would not be able to reset to its cocked position. In other words, the sear and therefore the cocking-piece/striker would be released from the seared (cocked) position with nothing but the safety holding up the sear. This condition is extremely unsafe, as the sear and therefore the cocking-piece/striker would be resting on the safety, poised to fire when the safety selector is switched “off.” To put it another way, the sear would become the “trigger,” and when the safety selector is switched “off” (back to “fire”) the rifle will fire or discharge of its own accord without the trigger being pulled.
It should be pointed out that this type of safety that cams the sear up off of the trigger can wear out with use due to, for example, scraping against the sear. That is to say, despite the safety being properly manufactured and functioning properly initially, the safety can be rendered “unsafe” simply by use, to say nothing of abuse.
Typically the safety selectors of military bolt action rifles, while mechanically very reliable, are inconveniently located on the upper rear of the bolt-group/bolt-sleeve. This location is directly in line with the rifle sights. Consequently, the shooter's view of the sights is blocked when moving the safety selector from “safe” to “fire,” thus disturbing his aim. When a telescopic sight is employed on a rifle with this type of safety it is often difficult to reach the safety selector as there can be very little room under the rear of the scope. Also, these types of safeties (on the bolt-sleeve) typically require the shooter to make a relatively large hand movement to set/reset the safety selector, again resulting in the disturbance of aim.
The safety selectors of most single-stage triggers are usually more conveniently located. The knobs of such selectors are usually located at the rear of the actions, either directly behind, or along-side the receivers. In these locations the selector knobs can usually be actuated without requiring the shooter to move more than his thumb so there need be no disturbance to his or her aim. However, these types of safeties typically do not block the movement of the trigger when set to “safe.” This is important as there is no tactile indication to the shooter that the safety is set on “safe” while the trigger is pulled attempting to fire. This can result in the shooter missing the opportunity to hit his patiently waited for, and carefully aimed at, target. While it might seem improbable that a shooter would be “unaware” (or forget) that his rifle safety selector is set to “safe,” this scenario is far more common than one might expect, especially in high stress, excitement, combat and/or hunting situations. In some bolt action rifles that employ bolt-sleeve safeties, whether provided with two-stage or single-stage triggers, pulling the trigger with the safety on “safe,” permits the striker group to snap forward with a noisy “click” into a safety notch in the bolt-sleeve but not firing. The first thought of a shooter under these circumstances may be to wonder if there has been a miss-fire or other malfunction. Typical miss-fire procedure is to wait thirty seconds before opening the bolt to insure that a hang-fire is not occurring. Thirty seconds is (hopefully) long enough to insure a miss-fire isn't really a hang-fire, because unlocking the bolt on a hang-fire can be lethal to the shooter, let alone destroying the rifle. Given that the shooter now realizes that the “click” was not a miss-fire but that the safety is on “safe,” then in order to “re-prepare” the rifle to fire, the bolt handle must be raised, requiring time and motion and making more noise, to re-cock the striker, then the bolt must be closed again, yet more time and motion and making yet more noise. Only then can the bolt-sleeve safety be moved to “fire,” with yet more time and motion. In a tactical scenario this consumption of several noisy seconds could result in failure of the mission, as well as exposing and endangering the shooter.
The operation of the novel safety selector completely eliminates the time, motion and noise problem described in the above paragraph. Firstly, the novel trigger/safety blocks the movement of the trigger immediately indicating to the shooter that the safety selector is set to “safe.” Secondly, because the striker is not allowed to move, the firing mechanism always remains cocked. Lastly, the novel safety selector's knob is conveniently located, requiring only minimal movement to actuate.
Briefly reviewed, the advantage of conventional prior art two-stage triggers is that they excellently meet the primary and secondary requirements for a rifle trigger by preventing the rifle from accidentally discharging. The disadvantages of prior art two-stage triggers are: 1) prior art two-stage military triggers inherently cannot provide lightweight trigger-pulls; 2) mass produced prior art two-stage military triggers cannot safely provide a crisp trigger-pull without being “gunsmithed”; and 3) prior art military two-stage triggers are equipped with inconvenient bolt-sleeve safeties.
The advantages of prior art single-stage triggers are: 1) prior art single-stage triggers can provide crisp, lightweight trigger-pulls; and 2) prior art single-stage triggers are inherently amenable to incorporation of ergonomically convenient safety selectors. The major disadvantage of prior art single-stage triggers is that they invariably provide only a few thousandths of an inch of engagement between the trigger and the sear when the rifle is cocked, and are therefore prone to accidental discharge. One type of single stage trigger attempts to solve the problem of accidental discharge of single-stage triggers by interposing a secondary sear-blocker co-axial with, and nested within the trigger. In order to fire a rifle with the aforementioned single stage trigger, the secondary sear-blocker, which protrudes through the front of the trigger, is depressed by the trigger finger prior to contacting/depressing the actual trigger. Depressing the secondary sear-blocker moves the secondary sear-blocker out of the path of the sear so that as the trigger finger continues to move rearward, the trigger finger contacts and depresses the trigger proper, firing the rifle in the usual manner. The function of the sear-blocker is to arrest the sear in the event the rifle is jarred enough to cause the trigger to release the sear unexpectedly.
This single stage trigger design effectively prevents accidental firing if the rifle is dropped. However, when this single stage trigger performs its safety function, it is necessary to raise and lower the bolt handle to re-cock the rifle before it can be fired. This means that if the rifle is sufficiently jarred so that the sear drops off the trigger, the rifle is not immediately fireable. This is an undesirable condition at best, especially if the shooter is unaware that it has occurred.